Reconstituted drug sheet embossing

Abstract

A system for embossing a reconstituted drug sheet of at least a drug embedded in a binder, having a determined sheet thickness with a set of embossing rollers in view of obtaining a pre-rod drug sheet with at least a folding enabling zone and at least a stiffening zone, each extending as a corresponding stripe on the pre-rod drug sheet in a feed direction through the set of embossing rollers, and in view of preserving an integrity of the pre-rod drug sheet. The system comprises an embossing device with the set of embossing rollers comprising at least a first and a second embossing roller separated by a nip, and configured to receive the reconstituted drug sheet in the feed direction into the nip, patrix-matrix embossing features of positive and negative projections, on the first and the second embossing rollers, whereby each of the patrix and matrix embossing features on the first embossing roller has a corresponding congruent counterpart on the second embossing roller, producing the nip to have a substantially constant value; each of the patrix and matrix embossing features on the first embossing roller and on the second embossing roller has a structure profile in which any curvature radius has a minimum value of 40 µm, and any profile depth or profile height is smaller than twice the determined sheet thickness, thereby enabling the patrix and matrix embossing features on the first embossing roller and on the second embossing roller to consistently and gaplessly be in contact with both sides of the reconstituted drug sheet in the nip. Further, the at least one of the folding enabling zone and the stiffening zone comprises respectively folding enabling embossing features and stiffening embossing features as patrix-matrix embossing features, aligned on the first and second embossing roller in a radial manner configured to emboss the corresponding stripe on the pre-rod drug sheet.

Description

[0001] Reconstituted drug sheet embossing

[0002] Technical Field of Invention

[0003] The invention is in the field of embossing of a reconstituted drug sheet of at least a drug embedded in a binder, in view of obtaining a pre-rod drug sheet with at least a folding enabling zone and at least a stiffening zone, at least one of which comprises embossed structures, taking into account particularities and material properties of the reconstituted drug sheet for the embossing.

[0004] Background Art

[0005] US publication US2020 / 0138095A1, describes a method for the production of sheetlike tobacco material. Other terms for sheet materials like the sheet-like tobacco material as used in the present description is a "reconstituted drug sheet " and "prerod drug sheet", the tobacco being just an example of a drug that can be embedded in a binder to produce the reconstituted drug sheet. The publication also discusses a crimping process and some negative effects that crimping may have on the material, such as a fly-out effect which occurs when the material is overextended by the crimping, and then offers specific solution for crimping which prevents the overextending, namely the use of a first and a second roller, where the first roller has a corrugation pattern defined by ridges on its surface and the second roller acts as counter roller for the first roller and has a softer surface than the first roller.

[0006] The invention aims at providing an alternative solution to the method of manufacturing a crimped drug sheet of prior art, in which any overextending of the material is prevented.

[0007] The invention further aims at providing an alternative solution to the method of manufacturing of a pre-rod drug sheet, in which a folding and a forming of the pre-rod drug sheet into a drug containing rod is facilitated, whereby any overextending of the pre-rod drug sheet is prevented and the stiffness of the produced rod is enhanced.

[0008] Summary of Invention

[0009] Accordingly, in a first aspect, the invention provides a method for embossing with a set of embossing rollers a reconstituted drug sheet of at least a drug embedded in a binder, having a determined sheet thickness in view of obtaining

[0010] - a pre-rod drug sheet with at least a folding enabling zone and at least a stiffening zone, each extending as a corresponding stripe on the pre-rod drug sheet in a feed direction through the set of embossing rollers,

[0011] - the pre-rod drug sheet being intended to being folded into a rod, the rod being for use in a drug delivery product,

[0012] - at least one of the folding enabling zone and the stiffening zone comprising embossed structures aligned in the feed direction, the embossed structures being configured depending on whether they are in the folding enabling zone or the stiffening zone, as folding enabling embossed structures and stiffening embossed structures to enable the folding of the pre-rod drug sheet or the stiffen the rod respectively, and in view of preserving an integrity of the pre-rod drug sheet. The method comprises providing the reconstituted drug sheet, providing an embossing device with the set of embossing rollers comprising at least a first and a second embossing roller separated by a nip, feeding the reconstituted drug sheet in the feed direction into the nip, and providing patrix-matrix embossing features of positive and negative projections, on the first and the second embossing rollers. Each of the patrix and matrix embossing features on the first embossing roller has a corresponding congruent counterpart on the second embossing roller, producing the nip to have a substantially constant value, each of the patrix and matrix embossing features on the first embossing roller and on the second embossing roller has a structure profile in which any curvature radius has a minimum value of 40 pm, and any profile depth or profile height is smaller than twice the determined sheet thickness, thereby enabling the patrix and matrix embossing features on the first embossing roller and on the second embossing roller to consistently and gaplessly be in contact with both sides of the reconstituted drug sheet in the nip. The method further comprises providing for the at least one of the folding enabling zone and the stiffening zone respectively folding enabling embossing features and stiffening embossing features as patrix- matrix embossing features, and aligning them on the first and second embossing roller in a radial manner configured to emboss the corresponding stripe on the prerod drug sheet, and. embossing the reconstituted drug sheet in the nip to obtain the pre-rod drug sheet.

[0013] In a preferred embodiment, the reconstituted drug sheet comprises reconstituted tobacco.

[0014] In a preferred embodiment, the method further comprises providing a bobbin of reconstituted drug sheet; and unwinding the reconstituted drug sheet towards the set of embossing rollers.

[0015] In a preferred embodiment, the method further comprises machining surfaces of patrix and matrix embossing features to provide them with a surface roughness Rawith a value equal or smaller than 1 pm.

[0016] In a preferred embodiment, the method further comprises spraying the reconstituted drug sheet with a humectant prior to feeding the reconstituted drug sheet in the feed direction into the nip, in order to improve a sheet cohesion and prevent an occurrence of sheet breakage and defective areas on the reconstituted drug sheet.

[0017] In a preferred embodiment, the method according further comprises generating a gas stream and directing the gas stream towards the nip between the first and the second embossing rollers, the gas being any one from a list comprising hot air, water vapor, a gaseous matter, the gas locally heating the nip between the two embossing rollers, configured to facilitate a detachment of the pre-rod drug sheet from the embossing rollers, and preventing an occurrence of sheet breakage and defective areas.

[0018] In a preferred embodiment, the method further comprises providing an embossing roller cleaning tool in form of scrappers attached to a support of the embossing rollers, and configured to apply a scrapper edge congruent to the embossing features on any one of the embossing rollers, and remove potential debris originating from the reconstituted drug sheet from the embossing roller.

[0019] In a preferred embodiment, the method further comprises providing stiffening patrix- matrix embossing features, whereby on one roller the patrix embossing features are configured to form protruding segments of ridges distinct from each other, and oriented under an angle in a range of 30° to 90° with respect to a radial orientation.

[0020] In a preferred embodiment, the method further comprises providing stiffening patrix- matrix embossing features, whereby on one roller the patrix embossing features are configured to form protruding segments of ridges distinct from each other and extending from one longitudinal side of the stripe to an opposite side of the stripe, and oriented under an angle in a range of 30° to 90° with respect to a radial orientation.

[0021] In a preferred embodiment, the method further comprises providing folding patrix- matrix embossing features, whereby on one roller the patrix embossing features are configured to form at least a protruding ridge on a surface of the one embossing roller, whereby the at least one protruding ridge is any one of continuous, and discontinuous, the at least one protruding ridge being radially oriented around the one embossing roller. In a second aspect, the invention provides a system for embossing a reconstituted drug sheet of at least a drug embedded in a binder, having a determined sheet thickness with a set of embossing rollers in view of obtaining

[0022] - a pre-rod drug sheet with at least a folding enabling zone and at least a stiffening zone, each extending as a corresponding stripe on the pre-rod drug sheet in a feed direction through the set of embossing rollers,

[0023] - the pre-rod drug sheet being intended to being folded into a rod, the rod being for use in a drug delivery product,

[0024] - at least one of the folding enabling zone and the stiffening zone comprising embossed structures aligned in the feed direction, the embossed structures being configured depending on whether they are in the folding enabling zone or the stiffening zone, as folding enabling embossed structures and stiffening embossed structures to enable the folding of the pre-rod drug sheet or to stiffen the rod respectively, and in view of preserving an integrity of the pre-rod drug sheet. The system comprises an embossing device with the set of embossing rollers comprising at least a first and a second embossing roller separated by a nip, and configured to receive the reconstituted drug sheet in the feed direction into the nip, patrix-matrix embossing features of positive and negative projections, on the first and the second embossing rollers, whereby each of the patrix and matrix embossing features on the first embossing roller has a corresponding congruent counterpart on the second embossing roller, producing the nip to have a substantially constant value; each of the patrix and matrix embossing features on the first embossing roller and on the second embossing roller has a structure profile in which any curvature radius has a minimum value of 40 pm, and any profile depth or profile height is smaller than twice the determined sheet thickness, thereby enabling the patrix and matrix embossing features on the first embossing roller and on the second embossing roller to consistently and gaplessly be in contact with both sides of the reconstituted drug sheet in the nip. Further, the at least one of the folding enabling zone and the stiffening zone comprises respectively folding enabling embossing features and stiffening embossing features as patrix-matrix embossing features, aligned on the first and second embossing roller in a radial manner configured to emboss the corresponding stripe on the pre-rod drug sheet.

[0025] In a preferred embodiment, the system further comprises a bobbin of reconstituted drug sheet configured to unwind the reconstituted drug sheet towards the set of embossing rollers.

[0026] In a preferred embodiment, surfaces of the patrix-matrix embossing features are configured to have a surface roughness Rawith a value equal or smaller than 1 pm.

[0027] In a preferred embodiment, the system further comprises a humectant spraying system configured for spraying the reconstituted drug sheet with a humectant prior to feeding the reconstituted drug sheet in the feed direction into the nip, in order to improve a sheet cohesion and prevent an occurrence of sheet breakage and defective areas on the reconstituted drug sheet.

[0028] In a preferred embodiment, the system further comprises a blower unit configured to generate a gas stream and to direct the gas stream towards the nip between the first and the second embossing rollers, the gas being any one from a list comprising hot air, water vapor, a gaseous matter, the gas locally heating the nip between the two embossing rollers, configured to facilitate a detachment of the pre-rod drug sheet from the embossing rollers, and preventing an occurrence of sheet breakage and defective areas.

[0029] In a preferred embodiment, the system further comprises an embossing roller cleaning tool in form of scrappers attached to a support of the embossing rollers, and configured to apply a scrapper edge congruent to the embossing features on any one of the embossing rollers, and remove potential debris originating from the reconstituted drug sheet from the embossing roller. In a preferred embodiment, the stiffening patrix embossing features on one roller are configured to form protruding segments of ridges distinct from each other, and oriented under an angle in a range of 30° to 90° with respect to a radial orientation.

[0030] In a preferred embodiment, the stiffening patrix embossing features on one roller are configured to form protruding segments of ridges distinct from each other and extending from one longitudinal side of the stripe to an opposite side of the stripe, and oriented under an angle in a range of 30° to 90° with respect to a radial orientation.

[0031] In a preferred embodiment, the folding patrix embossing features on one roller are configured to form at least a protruding ridge on a surface of the one embossing roller, whereby the at least one protruding ridge is any one of continuous, and discontinuous, the at least one protruding ridge being radially oriented around the one embossing roller.

[0032] In a preferred embodiment, the first embossing roller and the second embossing roller consist of a bulk metallic matter and exhibit a surface hardness larger than 50 HRC.

[0033] In a preferred embodiment, at least one of the first embossing roller and the second embossing roller is coated with a vacuum-deposited hard-coating, which exhibits a coating thickness smaller than 10 pm and a coating hardness greater than 500 MPa, and which belongs to a list containing diamond-like carbon, nitrides, carbides, oxides, and combinations thereof. Brief Description of the Figures

[0034] The invention will be better understood through the detailed description of preferred embodiments of the invention, and in reference to the Figures, wherein

[0035] Figure 1 depicts a cross-section from a reconstituted drug sheet according to an example embodiment of the invention;

[0036] Figure 2(A) schematically depicts a cross-section of an embossed pre-rod drug sheet according to an example embodiment of the invention, whereas Figure 2(B) schematically depicts a cross-section of a crimped reconstituted drug sheet according to an example of prior art;

[0037] Figure 3 schematically illustrates an embossing set-up according to an example embodiment of the invention;

[0038] Figure 4 schematically illustrates a process step of cutting a rod of reconstituted drug sheet into individual pieces;

[0039] Figures 5(A) and 5(B) illustrate embossing rollers in various possible configurations according to example embodiments of the invention;

[0040] Figures 6(A)-6(C) contain views of examples for quick-exchange devices configured for housing a set of embossing rollers according to example embodiments of the invention;

[0041] Figure 7 represents a set of embossing rollers configured for embossing a reconstituted drug sheet according to an example embodiment of the invention;

[0042] Figure 8 represents a set of embossing rollers according to an example embodiment of the invention;

[0043] Figure 9 represents a set of embossing rollers according to an example embodiment of the invention;

[0044] Figure 10 represents a set of embossing rollers according to an example embodiment of the invention;

[0045] Figure 11 schematically depicts in a cross-section a detail from a nip between embossing rollers according to an example embodiment of the invention; Figure 12 contains a schematical top view of a pre-rod drug sheet embossed according to an example embodiment of the invention;

[0046] Figure 13 contains an example of an embossed pre-rod drug sheet according to an example of the invention and a cross-section view at a surface of the embossing rollers;

[0047] Figure 14 contains an example of an embossed pre-rod drug sheet according to an example of the invention and a cross-section view at a surface of the embossing rollers;

[0048] Figure 15 contains an example of an embossed pre-rod drug sheet according to an example of the invention and a cross-section view at a surface of the embossing rollers;

[0049] Figure 16 contains an example of an embossed pre-rod drug sheet according to an example of the invention and a cross-section view at a surface of the embossing rollers;

[0050] Figure 17 shows a schematic illustration of an embossed pre-rod drug sheet exhibiting a defective area;

[0051] Figures 18(A) and 18(B) each schematically illustrate an embossing roller and a cross-section view at a surface of the embossing roller;

[0052] Figure 19 schematically illustrates an embossing set-up that comprises a humectant spraying system according to an example embodiment of the invention;

[0053] Figure 20 schematically illustrates an embossing set-up that comprises a blower unit according to an example embodiment of the invention;

[0054] Figure 21 contains a view of a system for manufacturing an embossed pre-rod drug sheet with an example embodiment of an embossing roller cleaning tool in form of scrappers;

[0055] Figure 22 illustrates a preferred embodiment of a system for manufacturing an embossed pre-rod drug sheet according to the invention;

[0056] Figure 23 schematically illustrates how a drug containing rod element may be mounted to a filtering element in order to obtain a cigarette according to prior art; Figure 24 schematically illustrates a structure of an inhalable drug delivery device; and

[0057] Figure 25 contains a flowchart illustrating the method according to the invention in a preferred embodiment.

[0058] Same references will be used to reference same or similar features throughout the set of Figures.

[0059] Detailed Description of Preferred Embodiments of the Invention

[0060] Tobacco dust, tobacco stems and leaf scraps have been used in the past to produce reconstituted tobacco sheets, which are an example of the reconstituted drug sheet of a drug embedded in a binder, but have met with mixed success.

[0061] Like whole leaf tobacco, when reconstituted tobacco sheets are cut into pieces, some degree of breakage may occur thus creating tobacco dust as a by-product. The ability of the reconstituted tobacco sheet to withstand the rigors of processing with minimal tobacco dust by-product formation is a highly desirable characteristic since the loss of tobacco material would be lessened and the need to produce additional reconstituted tobacco sheets to meet a constant demand would be minimized. In that regard, the costs associated with the manufacturing of cigarettes and other smoking articles may be decreased.

[0062] A problem common to all reconstituted drug sheets of a drug embedded in a binder and in particular for the reconstituted tobacco sheets that have been prepared by the processes known previously, has been pitting and non-uniform sheet thickness which affects the survivability of the sheets. Moreover, the ability to initiate and terminate these processes in a rapid and efficient manner has not been demonstrated by the processes previously developed. Besides tobacco leaves, also homogenized tobacco material is used. This homogenized tobacco material is typically manufactured from parts of the tobacco plant that are less suited for the production of cut filler, like, for example, tobacco stems or tobacco dust. Typically, tobacco dust may be created as a side product during the handling of the tobacco leaves during manufacture.

[0063] While the crimping process already mentioned in the background section herein above, is helpful for compressing and folding the crimped drug sheet into a rod that is subsequently cut in sticks that will fit into aerosol generating articles, such as for example cigarettes, the crimping process may also influence the amount of air contact, the Resistance To Draw (RTD), the rod stiffness, or others, and, hence, it is directly experienced by the users of the aerosol generating articles.

[0064] According to the nature of the material of the reconstituted drug sheet, in particular a tobacco cast leaf, the crimping process may produce corrugations in the reconstituted drug sheet, in form of ridges, that in turn cause overextended areas in the corrugated reconstituted drug sheet, that could be quite localized or not. In the overextended areas, the corrugated reconstituted drug sheet can become very thin compared to the overall thickness of the reconstituted drug sheet, especially in areas corresponding to a top of the ridge and in a bottom of a corresponding trough where it is compressed, thus bending lines may form. These bending lines may be considered as weak parts of the corrugated reconstituted drug sheets that can be torn during further processing in case of tension in the corrugated reconstituted drug sheet.

[0065] A shredding of the corrugated reconstituted drug sheet in the overextended areas may cause the formation of moving particles within a rod of material formed gathering the crimped reconstituted drug sheet. This phenomenon is known as fly-out effect, and it may cause a negative user experience when the user is smoking the aerosol generating article including the rod. Sheets of homogenized tobacco material may comprise one or more intrinsic binders, that is tobacco endogenous binders, one or more extrinsic binders, that is tobacco exogenous binders, or a combination thereof to help agglomerate the particulate tobacco; alternatively, or in addition, sheets of homogenized tobacco material may comprise other additives including, but not limited to, tobacco and non-tobacco.

[0066] A helical structure of the less crimped areas between the ridges can effectively bind particles which inadvertently were detached in the sheet of material and could cause an undesired fly-out effect.

[0067] Figure 1 depicts a cross-section from a reconstituted drug sheet 100 of at least a drug embedded in a binder according to the invention. The depicted reconstituted drug sheet 100 has a substantially constant sheet thickness d and comprises mainly drug-containing particles 101 , which are embedded in a binder 102 that acts as cohesive agent. Inherent to the fabrication process of the reconstituted drug sheet 100, the reconstituted drug sheet 100 may contain pits 103, e.g., air bubbles entrapped and embedded in a volume of the binder 102. In a particular execution, the reconstituted drug sheet 100 may be a sheet of reconstituted tobacco, whereas the thickness d may vary between 0.1 mm and 0.5 mm, preferably between 0.2 mm and 0.3 mm. Furthermore, the drug-containing particles 101 may contain tobacco and they may be finely ground to reach typical dimensions in a range between 20 pm and 200 pm.

[0068] Figure 2(A) schematically depicts a cross-section of an embossed reconstituted drug sheet 200 that has been embossed according to the invention, i.e. , with a set of embossing rollers, in which the drug-containing particles 101 and the binder 102 are indicated. A particular attention is given to the thickness d of the embossed sheet, which remains substantially constant over the entire cross-section as a result of the proper settings for the embossing rollers, which will be detailed in a further point of the description of the invention. Figure 2(B) schematically depicts a cross-section of a reconstitute drug sheet 201 that has been crimped according to the prior art. A particular attention shall be given to a tapering 202, where the crimped reconstituted drug sheet 201 is characterized by a thickness d’, whereas d’ < d. The occurrence of the tapering implies the presence of a reconstituted drug sheet overextension in this particular region, which itself represents a potential point of rupture for the reconstituted drug sheet during its further processing to obtain a drug delivery device. This potential rupture of the reconstituted drug sheet crimped according to the prior art may be particularly disadvantageous as loose debris in the drug delivery device and may have a negative impact on the use of the drug delivery device.

[0069] Referring to Figure 3 this illustrates an embossing set-up 300 according to an example embodiment of the invention. The embossing set-up 300 is configured for embossing a reconstituted drug sheet 302, and the embossed reconstituted drug sheet, now called pre-rod drug sheet 306 is further configured to be folded and to obtain a rod of a drug delivery device. The embossing set-up 300 comprises a set of embossing rollers, i.e., a first embossing roller 304 and a second embossing roller 305, and is configured to realize embossing on the reconstituted drug sheet 302. The first embossing roller 304 and the second embossing roller 305 may optionally be mounted in an embossing head 303 (construction details not represented) and are configured to cooperate with each other to emboss in a nip 312 the reconstituted drug sheet 302 fed between the first embossing roller 304 and the second embossing roller 305. A synchronization of the embossing rollers 304 and 305 may be implemented in various manners, one of which is suggested in Figure 3 and is not limitative for the embossing set-up 300, which comprises toothed wheels on the extremities of the rollers, which cooperate with each other. Other embodiments for synchronization may for example involve a servo-control mechanism (not illustrated) which controls angular positions of each roller relative to the other roller, or a combination of toothed wheels and the servo-control mechanism. An optional bobbin dispensing device (not illustrated) may be configured to carry a bobbin 301 with a web of reconstituted drug sheet and unwind it out towards the embossing head 303. The embossing set-up 300 may belong to a production line for manufacturing a drug containing device of length L (device and length not represented in Figure 3). The online production line may further comprise a compacting device 307 comprising a funnel 308 into which the embossed pre-rod drug sheet 306 is fed, folded and formed into a rod 310 output by the compacting device 307. The rod 310 may be pulled by means of a pulling jig 309 to a further process step 311 of cutting.

[0070] Figure 4 illustrates the further process step 311 of cutting the drug-containing rod 310 obtained from folding and forming the embossed pre-rod drug sheet into individual pieces comprising, as an example, two rod elements 402 each, having the length L, by means of a cutting device 401. In preferred embodiments, the value of the length L may vary in a range between 10 mm and 200 mm, whereas the diameter (not represented) of the drug-containing rod may mainly vary in a range, but not limited to, between 5 mm and 20 mm.

[0071] As for Figure 5(A), this illustrates an example embodiment for any one of embossing rollers 304 and 305, which comprises a rotation axis 500, a roller surface 501 and a toothed wheel 502 at one extremity of the embossing roller 304, 305 enabling the embossing roller 304, 305 to be driven by a motor assembly having a corresponding toothed wheel (not represented in Figure 5). The roller surface 501 may carry embossing features (not represented) which protrude from or recess in a base surface (features not explicitly represented) of the embossing roller 304, 305. Examples of embossing features will be given further in the description of the invention. Referring now to Figure 5(B), this shows a further example embodiment for any one of embossing rollers 304 and 305, which is similar to that of Figure 5(A), except that it doesn't comprise any toothed wheel. In this example the embossing roller 304, 305, is typically driven by a servo motor mechanism (not represented) that directly rotates the rotation axis 500.

[0072] Figures 6(A) - 6(C) contain views of examples for quick-exchange devices configured for housing a set of embossing rollers according to the invention. The embossing rollers 304 and 305 may be removably housed in a quick-exchange device, generically illustrated under reference 600 in Figure 6(A). In a preferred embodiment 606 of such a quick-exchange device, an axle of at least one of the rollers 304, 305 is movable in all three coordinate directions (not illustrated) in order to allow a self-synchronization of the embossing rollers. As shown in Figure 6(B), the quick-exchange device comprises a frame 601 having two seats intended to receive respective roller fixtures 602 and 603, whereas the roller fixture 603 serves for mounting the roller 305, which is driven by a here non-represented external drive, and roller fixture 602 serves for mounting the roller 304. In a further preferred embodiment 607 shown in Figure 6(C) of the quick-exchange device, the rollers 304 and 305 are mounted in a cassette 604, which contains means (not represented) for adjusting and correcting the positions and the rotation axes of the rollers 304 and 305, and which is removably mounted in a frame 605. In preferred embodiments, the roller 304 is driven by the externally driven roller 305 via gearwheels (not represented) located at one end of the rollers. However, other synchronizing means, e.g., electric servomotors, may also be used.

[0073] Figure 7 contains a view of a system for embossing a reconstituted drug sheet with a schematical illustration of two different types of gears for driving and synchronizing the embossing rollers according to the invention. Figure 7 illustrates preferred embodiments for driving and synchronizing the embossing rollers 304 and 305, belonging to the embossing roller system 303, according to the invention. A feed direction of the reconstituted drug sheet 302 and of the embossed pre-rod drug sheet of 306 is given by the arrows 702, whereas Figure 7 also illustrates a further preferred embodiment 700, in which helicoidal gears 701 are used to drive and synchronize the embossing rollers instead of the toothed wheels depicted for the embossing rollers system 303.

[0074] Figure 8 represents a set of embossing rollers 801 , 802, bearing protrusion and recess embossing features (not illustrated), each comprising at a corresponding extremity a toothed wheel 803, 804, the teeth of which intertwine to synchronously drive the embossing rollers 801 , 802, to rotate about respective rotation axes 805, 806. The embossing rollers 801, 802, further each comprise two ring-shaped shoulders 807, 808, one towards each extremity of the respective embossing roller 801, 802, and configured such that a ring-shaped shoulder on one embossing roller faces a corresponding ring-shaped shoulder of the opposite embossing roller. The ring-shaped shoulders 807, 808, are generally designed to form a ring which is centered on the rotation axis of the embossing roller, whose circumference protrudes from a base surface of the embossing roller where it is located. This level of detail is not illustrated in Figure 8 to maintain a better readability.

[0075] Figure 9 represents the set of embossing rollers 801 , 802 of Figure 8 but in a different perspective, together with two magnified views 901 , 902, of areas where the ring-shaped shoulders 807 and 808 are resting on each other as may be the case during embossing. This is substantiated by distance 903 between the ring-shaped shoulders 807 and 808 being 0, while a nip 904 is maintained between the embossing rollers 801 and 802 with a determined nip width value n separating a base surface 906 of the embossing roller 801 from an opposite base surface 905 of the embossing roller 802. The base surfaces are schematically represented in the views 901 and 902 and they do not comprise any embossing features in the example of Figure 9. The determined nip width value n of the nip 904 enables to insert a reconstituted drug sheet in it (reconstituted drug sheet not represented) for embossing.

[0076] In a further example represented in Figure 10 the ring-shaped shoulders of Figure 9 may be replaced by radial recesses 1001 and 1002, which each form recesses in the embossing rollers 801 and 802 respectively as compared to the base surfaces 1005 and 1006. Hence, when the embossing rollers 801 and 802 are pressured one towards the other, as is depicted by arrows 1007 in the radial recesses 1001 and 1002, their base surfaces 1005 and 1006 may be coming into contact such that a distance 1003 tends to become similar to that of a sheet of material inserted therein for embossing (not illustrated), and a distance 1004 between radial recesses 1001 and 1002 facing each other from one embossing roller to the other is greater than 0. The pressure depicted by the arrows 1007 may be exerted by pressuring means comprised in the embossing set-up (not illustrated) as is well known in the prior art, for example by hydraulic pressuring means.

[0077] Figure 11 schematically depicts in a cross-section a detail from an example nip 1106 between the embossing rollers 304 and 305, that may be called first and second embossing rollers, also indicating their respective rotation senses 1100 and 1101 during the embossing and their involutes 1102 and 1103. The reconstituted drug sheet 302, from which a magnified cross-section view 1105 is also shown in Figure 11, has a feed direction indicated by the arrows 1104 and the result of the embossing is illustrated as the embossed pre-rod drug sheet 306.

[0078] The first and second embossing rollers 304 and 305 are configured for patrix-matrix embossing and each comprises embossing features of positive 1107 and negative 1108 projections. On each of the first and the second embossing rollers 304 and 305, each of the patrix and matrix (no matrix on the first roller 304 illustrated in the figure) embossing features on the first embossing roller 304 has a corresponding congruent counterpart on the second embossing roller 305, producing the nip 1106 to have a substantially constant value. This enables the patrix and matrix embossing features on the first embossing roller 304 and on the second embossing roller 305 to consistently and gaplessly be in contact with both sides of the reconstituted drug sheet 302 in the nip 1106.

[0079] When stating that the nip has a substantially constant value, this means that it is aimed to attain this constant value, but however, due to machining uncertainties in producing the embossing rollers, the fixtures for mounting the rollers in an embossing head, and the patrix and matrix embossing features, it may happen that minute variations or errors of the nip occur, which typically would not exceed 5% of the aimed constant value of the nip.

[0080] Referring to the pre-rod drug sheet embossed according to the invention (306) a schematical top view of an example is contained in Figure 12, with stripes of folding enabling zones and stiffening zones. Each of folding enabling zones and stiffening zones may optionally comprise embossed structures, whereby for example the folding enabling zones comprise folding enabling embossed structures but the stiffening zones don't comprise any embossed structures, or the folding enabling zones don't comprise any folding enabling embossed structures but the stiffening zones comprise stiffening embossed structures. In another example both folding enabling zones and stiffening zones comprise respectively folding enabling embossed structures and stiffening embossed structures (embossed structures not represented). The feed direction experienced by the embossed pre-rod drug sheet 306 during the embossing process (embossing process not illustrated) is indicated by the arrow 1104. Successive folding enabling zones 1201 may be characterized by a spacing p between each other, and they may comprise folding-enabling embossed structures (not illustrated). In preferred embodiments, the spacing p may have values in a range between 0,5 mm and 5,0 mm, more typically between 0,5 mm and 2,5 mm. The folding-enabling embossed structures may be substantially parallel with the direction 1104 and they may be distributed continuously in one folding enabling zone 1201 to which they belong, or, in other preferred embodiments, they may exhibit discontinuities, i.e. , produce non-embossed interruptions between 2 consecutive embossed structures. Summarizing, a folding enabling zone 1201 may correspond in its entirety to the continuously distributed embossed structures, or it may comprise for example at least two parallel dashed lines of distinct folding enabling embossed structures, substantially parallel to 1104. Figure 12 illustrates also stiffening zones 1202, containing separated stiffening embossed structures (embossed structures not illustrated) in form of segments of protruded ridges, arranged in a homogeneous manner over a zone 1202, whereas the individual structures lie in a determined angle, preferably larger than 30° with respect to 1104.

[0081] Referring to the stiffening zones, it is known from the prior art that the stiffness (i.e., the perceived hardness) of a drug-containing rod is an important parameter influencing the perception of the quality of drug-containing products by consumers: a too soft or too hard drug-containing rod will not be experienced positively. The experienced stiffness of a drug-containing rod is consumer specific, thus subjective, and the design of a universal assessment method is not possible. However, rod stiffness experimental evaluation is possible and they relies on appling a force and on measuring a related displacement. In the here exposed case, due the particular structure of a reconstituted drug sheet of at least a drug embedded in a binder, the produced drug-containing rods tendentially exhibit a lower stiffness and any means to stiffen the produced drug-containing rod 310, i.e., the stiffening embossed structures situated in the stiffening zones 1202 are beneficial.

[0082] A preferred embodiment is exposed in Figure 13, which shows an embossed pre-rod drug sheet 306, embossed structures 1301, a non-embossed part 1303 of the prerod drug sheet, as well as a cross-section direction 1302. Figure 13 further contains a magnified cross-section 1304 of embossing rollers 304, 305 used for embossing the pre-rod drug sheet 306. The embossed structures 1301 may comprise protruded ridges arranged in a periodic manner described by dimensional period parameters I and I’. In preferred embodiments, the parameter I may have values in a range between 0,5 mm and 5,0 mm, more typically between 0,5 mm and 2,5 mm, whereas the parameter I’ may have values in a range between 2 mm and 25 mm, more typically between 5 mm and 15 mm. In the cross-sectional view 1304 we further see a zone of a nip between the embossing rollers 304 and 305 used to obtain the embossed pre-rod drug sheet 306 (sheet not illustrated in the view 1304), which further corresponds to a symbolic line illustrated by the cross-section direction 1302 along the embossed sheet 306, whereby the embossed structures 1301 correspond to ridges embossed by embossing features 1305. A height h of the embossing features 1305 is equally indicated in Figure 13, as well as a curvature radius R of an apex of the embossing features 1305. In preferred embodiments, the height h may have values smaller than 1 ,0 mm, more preferably smaller than 0,5 mm and, as previously mentioned and due to the material structure of the reconstituted drug sheet to be embossed and in order to prevent local overextension (e.g., 202 in Figure 2), the curvature radius R of the apex of the embossing features shall not go below a minimal value of 40 pm. Referring to the folding enabling zones 1201 and stiffening zones 1202, they are also depicted in Figure 13, whereas in this preferred embodiment the folding-enabling zones 1201 do not comprise any embossed structures, i.e., and hence is a continuous stripe of non-embossed pre-rod drug sheet parallel to the feed direction 1104, and the stiffening zones 1202 comprise distinct, periodically arranged embossed structures 1301, under an angle of 30° with respect to the direction 1104.

[0083] A further embodiment is exposed in Figure 14, which depicts an embossed pre-rod drug sheet 306, embossed structures 1401, 1402, a non-embossed part 1403 of the pre-rod drug sheet 306, as well a cross-section direction 1404. Figure 14 further contains a magnified cross-section 1405 of embossing rollers 304, 305 used for embossing the pre-rod drug sheet 306. The embossed structures 1401 may comprise continuous protruded ridges, substantially parallel with the feed direction 1104 and described by the dimensional period parameter I, whereas the embossed structures 1402 may be in form of segments of ridges, forming branches of the protruded ridge of embossed structures 1401 , arranged in a periodic manner described by the dimensional period parameter I’. In preferred embodiments, the parameter I may have values in a range between 0,5 mm and 5,0 mm, more typically between 0,5 mm and 2,5 mm, whereas the parameter I’ may have values in a range between 1 mm and 10 mm, more typically between 2 mm and 5 mm. In a cross-sectional view 1405 from a zone of a nip between the embossing rollers 304 and 305 used to obtain the embossed pre-rod drug sheet 306, which further corresponds to a symbolic line illustrated by the cross-section direction 1404 along the embossed pre-rod drug sheet 306, whereby embossed structures 1401 correspond to ridges embossed by the embossing features 1406 and the embossed structures 1402 correspond to ridges embossed by the embossing features 1407. The height h of the embossing features 1406 and 1407 is equally indicated in Figure 14, as well as the curvature radius R of the apex of the embossing features. In preferred embodiments, the height h may have values smaller than 1 ,0 mm, more preferably smaller than 0,5 mm and, as previously mentioned and due to the composite material structure of the reconstituted drug sheet to be embossed and in order to prevent local overextension (e.g., 202 in Figure 2), the curvature radius R of the apex of the embossing features shall not go below a minimal value of 40 pm. Referring to the folding enabling zones 1201 and stiffening zones 1202, they are also depicted in Figure 14, whereas in this preferred embodiment each of the folding-enabling zone 1201 comprises a continuous embossed stripe parallel to the feed direction 1104, and each of the stiffening zones 1202 consists of distinct branches, periodically arranged embossed structures, under an angle of 45° with respect to the direction 1104.

[0084] A further preferred embodiment is exposed in Figure 15, which depicts an embossed pre-rod drug sheet 306, embossed structures 1501 , 1502, a non-embossed part 1503 of the pre-rod drug sheet, interruptions 1504 between the embossed structures 1501 , as well a cross-section direction 1505. Figure 15 further contains a magnified cross-section 1506 of embossing rollers 304, 305 used for embossing the pre-rod drug sheet 306. The embossed structures 1501 may comprise protruded ridges, substantially parallel with the feed direction 1104, interrupted by the interruptions 1504, and described by the dimensional period parameter I, whereas the embossed structures 1502 may be in form of segments of ridges, forming of branches of the protruded ridge of embossed structures 1501, arranged in a periodic manner described by the dimensional period parameter I’. In preferred embodiments, the parameter I may have values in a range between 0,5 mm and 5,0 mm, more typically between 0,5 mm and 2,5 mm, whereas the parameter I’ may have values in a range between 1 mm and 10 mm, more typically between 2 mm and 5 mm. In a cross- sectional view 1506 from a zone of a nip between the embossing rollers 304 and 305 used to obtain the embossed pre-rod drug sheet 306, which further corresponds to a symbolic line illustrated by the cross-section direction 1505 along the embossed prerod drug sheet 306, whereby embossed structures 1501 correspond to ridges embossed by the embossing features 1507 and the embossed structures 1502 correspond to ridge embossed by the embossing features 1508. The height h of the embossing features 1507 and 1508 is equally indicated in Figure 15, as well as the curvature radius R of the apex of the embossing features. In preferred embodiments, the height h may have values smaller than 1 ,0 mm, more preferably smaller than 0,5 mm and, as previously mentioned and due to the material structure of the reconstituted drug sheet to be embossed and in order to prevent local overextension (e.g., 202 in Figure 2), the curvature radius R of the apex of the embossing features shall not go below a minimal value of 40 pm. Referring to the folding enabling zones 1201 and stiffening zones 1202, they are also depicted in Figure 15, whereas in this preferred embodiment each of the folding-enabling zone 1201 comprises embossed structures parallel to the feed direction 1104, and each of the stiffening zones 1202 consists of distinct branches, periodically arranged embossed structures, under an angle of 45° with respect to the direction 1104.

[0085] A preferred embodiment is further presented in Figure 16, which shows an embossed pre-rod drug sheet 306, embossed structures 1601 , a non-embossed part 1602 of the pre-rod drug sheet, as well as a cross-section direction 1603. Figure 16 further contains a magnified cross-section 1604 of embossing rollers 304, 305 used for embossing the pre-rod drug sheet 306. The embossed structures 1601 may comprise protruded ridges of variable lateral extension arranged in a periodic manner described by dimensional period parameters I (in a direction perpendicular to 1104) and p (in a direction parallel to 1104). In preferred embodiments, the parameter I may have values in a range between 0,5 mm and 5,0 mm, more typically between 0,5 mm and 2,5 mm, whereas the parameter p may have values in a range between 2 mm and 25 mm, more typically between 5 mm and 15 mm. In the cross-sectional view 1604 one further sees a zone of a nip between the embossing rollers 304 and 305 used to obtain the embossed pre-rod drug sheet 306 (sheet not illustrated in the view 1604), which further corresponds to a symbolic line illustrated by the cross-section direction 1603 along the embossed sheet 306, whereby the embossed structures 1601 correspond to ridges embossed by the embossing features 1605. A height h of the embossing features 1605 is equally indicated in Figure 16, as well as a curvature radius R of an apex of the embossing features 1605. In preferred embodiments, the height h may have values smaller than 1 ,0 mm, more preferably smaller than 0,5 mm and, as previously mentioned and due to the material structure of the reconstituted drug sheet to be embossed and in order to prevent local overextension (e.g., 202 in Figure 2), the curvature radius R of the apex of the embossing features shall not go below a minimal value of 40 pm. Referring to the folding enabling zones 1201 and stiffening zones 1202, they are also depicted in Figure 16, whereas in this preferred embodiment the folding-enabling zone 1201 comprise distinct, periodically arranged embossed structures 1601, parallel to the feed direction 1104, and the stiffening zones 1202 do not comprise any embossed structures. A situation that theoretically may occur during embossing and which is addressed in a preferred embodiment of the invention is illustrated in Figure 17, which schematically illustrates a cross-section 1700 of an embossed sheet 1702 of a reconstituted drug sheet that yet exhibits a defective area 1701. Referring to the structure of the embossed reconstituted drug sheet 1702, the drug-containing particles 101, the binder 102, and the air bubbles 103 entrapped and embedded in the binder volume are indicated in Figure 17. In the defective area 1701 , a discontinuity occurred in the embossed reconstituted drug sheet 1702 and the binder 102 and drug containing particles 101 became exposed and could potentially be further removed from the embossed reconstituted drug sheet 1702.

[0086] Referring now to the defective area 1701 , a debris part from the embossed reconstituted drug sheet, which may comprise further removed binder 102 and / or particles 101, may be found on an embossing roller used to obtain the embossed reconstituted drug sheet 1702, as illustrated in Figure 18. For illustration purposes, the second embossing roller 305 was chosen, but the following considerations may equally apply to the first embossing roller, not represented. The embossing features 1301 are schematically represented on the lateral surface of the roller 305, on which a debris 1801 that may originate from the embossed reconstituted drug sheet (not represented) is equally depicted in Figure 18(A). A view 1808 contains a detailed cross-section from the embossing roller 305 taken along a line 1800, wherein the debris 1801 is noticeable on the roller surface, in-between two adjacent embossing features. The primary (i.e., the original) roller surface is indicated by reference 1802, whereas the specific surfaces of the embossing features manufactured on the roller are indicated by the references 1803 and 1804. These surfaces of the embossing features 1301 are manufactured with a determined surface roughness and in a preferred execution of the invention they may be manufactured by laser machining, in which at least a focused laser beam impinging on the roller surface gradually and in a determined manner removes by melting and sublimation material from the embossing roller. Referring now again to the detailed view 1808, the surfaces 1803 and 1804 are represented with a schematically exaggerated not at scale surface roughness, to illustrate the idea the above-mentioned determined surface roughness is yet too high (i.e., Ra value about 2 pm and above) and that the corresponding asperities may impact on the integrity of the embossed drug sheet (not represented) and facilitate the detachment of a debris 1801 , which originates from a defective area 1701 (not illustrated), and which remains stuck on the embossing roller surface, as illustrated in Figure 18(A). The Figure 18(B) also depicts the embossing roller 305 with embossing features 1301 , as well as a line 1805 along which a detailed cross-section from the embossing roller is considered and depicted in the view 1809. The primary (i.e., the original) roller surface is indicated by reference 1802, whereas the specific surfaces of the embossing features manufactured on the roller according to the invention are indicated by the references 1806 and 1807. These surfaces of the embossing features 1301 are manufactured with a determined surface roughness and in a preferred execution this surface roughness shall be characterized by Ravalues smaller than 1 pm, preferably even smaller than 0,5 pm. These types of surfaces characterized by roughness values within this range may be obtained by anyone of laser machining, precision high-speed milling, and chemical etching.

[0087] Figure 19 illustrates a further preferred embodiment of the system that has similarities with the system in Figure 3, with a humectant spraying system according to the invention. Figure 19 illustrates a further preferred embodiment of an embossing set-up 1900 according to the invention as a part of an online production process, wherein the embossing set-up 303 is part of an online production line for manufacturing a drug containing rod element of length L (rod and length not represented). The online production line further comprises for example the compacting device 307 comprising the funnel 308 into which an embossed pre-rod drug sheet 1903 is fed, folded and formed into a rod 1904 output by the compacting device 307. The rod 1904 may be pulled by means of the pulling jig 309 to the further process step 311 of cutting. The production line contains the embossing system 303, according to the invention, to produce an embossed pre-rod drug sheet using the first embossing roller 304 and the second embossing roller 305. In a preferred embodiment illustrated in Figure 19 the reconstituted drug sheet 302 passes through a humectant spraying system 1901 , where a sheet surface 1902 is sprayed with a humidifying agent that will improve the sheet cohesion and prevent the occurrence of sheet breakage and defective areas, as described in Figures 17 and 18. As an option, the production line may comprise a bobbin dispensing device configured to carry the bobbin 301 with the web of reconstituted drug sheet 302 and unwind it out towards the humectant spraying system 1901 and the embossing set-up 303.

[0088] Figure 20 illustrates a preferred embodiment of the system for manufacturing an embossed pre-rod drug sheet according to the invention, where it is a part of an online production line for manufacturing a drug containing rod element. More precisely, Figure 20 illustrates a preferred embodiment of a system 2000 for manufacturing an embossed pre-rod drug sheet according to the invention, as a part of an online production line for manufacturing a drug containing rod element of length L (rod element and length not represented). The online production line further comprises for example the compacting device 307 comprising the funnel 308 into which a further embossed pre-rod drug sheet 2002 is fed, folded, and formed into a rod 2003 output by the compacting device 307. The rod 2003 may be pulled by means of the pulling jig 309 to the further process step 311 of cutting. The production line contains the embossing system 303, according to the invention, to produce the embossed pre-rod drug sheet 2002, whereas the first embossing roller 304 and the second embossing roller 305 are showed in Figure 20. In a further preferred embodiment, the online production line further comprises a blower unit 2001 installed such that it generates a gas stream and directs the gas stream towards the nip (not represented) between the first and the second embossing rollers, 304 and 305. The gas stream may be hot air, or water vapor, in generally a gaseous matter that locally heats the nip between the two embossing rollers and, facilitates the detachment of the embossed pre-rod drug sheet 2002 from the rollers 304, 305 and prevents the occurrence of sheet breakage and defective areas, as described in Figures 17 and 18. As an option, the production line may comprise the bobbin dispensing device configured to carry a bobbin 301 with a web of reconstituted drug sheet 302 and unwind it out towards the embossing set-up 303.

[0089] Figure 21 contains a view of a system for manufacturing an embossed pre-rod drug sheet with an example embodiment of an embossing roller cleaning tool in form of scrappers according to a preferred embodiment of the invention. In this example embodiment of the invention, the detachment of debris 1801 from the surfaces of rollers 304, 305 (embossing features not represented) is carried out by means of metallic (e.g., brass, hardened steel) or ceramic (e.g., oxides, nitrides, carbides) adapted-shape scrappers 2102 and 2103. The embossing rollers 304, 305 and the scrappers 2102, 2103 are respectively mounted on roller fixtures 602 and 603, which are themselves part of a quick-exchange device (not represented). However, the quick-exchange device is optional, and the scrappers may be attached to any form of roller supports. To obtain an optimal debris removal from the roller surfaces, the specific edge shape geometries 2104, 2105 of the scrappers 2102, 2103 respectively shall be congruent to the embossing features (not represented) present on the surfaces of the embossing rollers 304, 305. In a further embodiment, optional means 2101 of lateral displacement are provided for the roller fixture 602, in order to allow a self-synchronization of the embossing rollers, by maintaining the matching scrapper positions.

[0090] Figure 22 illustrates a preferred embodiment of the system for manufacturing an embossed pre-rod drug sheet according to the invention, where it is a part of an online production line for manufacturing a drug containing rod element. More precisely, Figure 22 illustrates a preferred embodiment 2200 of the system for manufacturing an embossed pre-rod drug sheet according to the invention, as a part of an online production line for manufacturing a rod element of length L (rod element and length not represented). The online production line further comprises for example the compacting device 307 comprising the funnel 308 into which an embossed prerod drug sheet 2206 is fed, folded, and formed into a drug containing rod 2207 output by the compacting device 307. The rod 2207 may be pulled by means of the pulling jig 309 to the further process step 311 of cutting. The production line contains an embossing system 2201, according to the invention, to produce the embossed reconstituted drug sheet 2206, whereas the first embossing roller 304 and the second embossing roller 305 are represented as components of the embossing system 2201. In a preferred embodiment, adapted-shape scrapes 2102, 2103 are mounted in the embossing system 2201 to clean the embossing roller 304, 305 from debris 1801 during the process of embossing. In a further embodiment, the embossing system 2201 includes air-depression cleaning systems 2202 and 2203, which are showed in Figure 22, as well as the removed debris 2204, 2205. As an option, the production line may comprise the bobbin dispensing device configured to carry a bobbin 301 with a web of reconstituted drug sheet 302 and unwind it out towards the embossing set-up 2201 according to the invention.

[0091] Figure 23 schematically illustrates how a drug containing rod element may be mounted to a filtering element in order to obtain a cigarette according to prior art. More precisely, Figure 23 schematically illustrates how a filtering element 2300, in a preferred embodiment initially obtained as two twin-filters 2300, may be mounted to drug containing rod elements 402 in order to obtain a cigarette 2302 according to prior art. Part (A) shows two twin-filter elements 2300, part (B) shows the two twinfilter elements 2300 positioned between drug-containing rod elements 402, and a filter paper 2301 being wound and glued around the two filter elements 2300 and partly over a part of each drug rod element 402, resulting in two twin-cigarettes 2302 shown in part (C). Part (D) shows one of cigarettes 2302 obtained after cutting the two twin-cigarettes in a middle 2303 thereof.

[0092] Figure 24 schematically illustrates a structure of an inhalable drug delivery device 2400 in parts (A) and (B), according to the prior art. Part (A) depicts a delivery system comprising a filtering element 2402 and a drug-containing component 2401 fabricated using a sheet of drug embedded in a binder embossed according to the invention. Part (B) depicts an inhalable drug delivery system comprising the drugcontaining component 2401 fabricated using a sheet of drug embedded in a binder embossed according to the invention, a cooling component 2403, and a filtering element 2402.

[0093] Figure 25 schematically illustrates a method according to an example embodiment of the invention. The method is for embossing with a set of embossing rollers

[0094] - a reconstituted drug sheet of at least a drug embedded in a binder, having a determined sheet thickness; in view of obtaining - a pre-rod drug sheet with at least a folding enabling zone and at least a stiffening zone, each extending as a corresponding stripe on the pre-rod drug sheet in a feed direction through the set of embossing rollers,

[0095] - the pre-rod drug sheet being intended to being folded into a rod, the rod being for use in a drug delivery product,

[0096] - at least one of the folding enabling zone and the stiffening zone comprising embossed structures aligned in the feed direction, the embossed structures being configured depending on whether they are in the folding enabling zone or the stiffening zone, as folding embossed structures and stiffening embossed structures to enable the folding of the pre-rod drug sheet or the stiffness of the rod respectively, and in view of preserving an integrity of the pre-rod drug sheet.

[0097] Accordingly, the method starts with a step 2501 of providing the reconstituted drug sheet 2500, and a step 2502 of providing an embossing device with the set of embossing rollers comprising at least a first and a second embossing roller separated by a nip. The method then implements a step 2503 of feeding the reconstituted drug sheet in the feed direction into the nip and providing 2504 patrix-matrix embossing features of positive and negative projections, on the first and the second embossing rollers.

[0098] Each of the patrix and matrix embossing features on the first embossing roller has a corresponding congruent counterpart on the second embossing roller, producing a nip having a substantially constant value. Each of the patrix and matrix embossing features on the first embossing roller and on the second embossing roller has a structure profile in which any curvature radius has a minimum value of 40 pm. Each of the patrix and matrix embossing features on the first embossing roller and on the second embossing roller has a structure profile in which any profile depth or profile height is smaller than twice the determined sheet thickness. This enables the patrix and matrix embossing features on the first embossing roller and on the second embossing roller to consistently and gaplessly be in contact with both sides of the reconstituted drug sheet in the nip. The method proceeds further with a step of providing 2505 for the at least one of the folding enabling zone and the stiffening zone corresponding folding embossing features and stiffness embossing features as patrix-matrix embossing features, and aligning them on the first and second embossing roller in a radial manner configured to emboss the corresponding stripe on the pre-rod drug sheet, and a step embossing 2506 the reconstituted drug sheet in the nip to obtain the pre-rod drug sheet 2507.

[0099] Glossary

[0100] As used herein, the term "sheet" denotes a laminar element having a width and length substantially greater than the thickness thereof.

[0101] In order to fully appreciate the present invention, the following terms are defined as indicated.

[0102] "Reconstituted drug sheet of a drug embedded in a binder" or "reconstituted drug sheet" -- a drug sheet of substantially uniform thickness and plasticity, which may be produced by the rolling and casting of drug particles that may be mixed with a cohesive agent or binder.

[0103] "Pre-rod drug sheet " -- a reconstituted drug sheet that has been embossed according to the invention and is ready to be transformed into a drug-containing rod.

[0104] "Rod" - an elongated product obtained from the pre-rod drug sheet, that may subsequently be cut in sticks that will fit into drug-containing aerosol generating articles.

[0105] "Stripe" -- an elongated, narrow band or strip of the pre-rod drug sheet defining either a folding enabling zone or a stiffening zone respectively having folding enabling and stiffening properties.

[0106] "Pit" or "pitting" -- an imperfection, cavity or crater often found in reconstituted tobacco sheets due to the presence of air trapped within the slurry matrix during casting.

[0107] "Reconstituted tobacco sheet" -- a tobacco sheet of substantially uniform thickness and plasticity that may be produced by the rolling or casting of tobacco dust, stems, by-products and the like that are finely ground and that may be mixed with a cohesive agent or binder.

[0108] "Pit" or "pitting" -- an imperfection, cavity or crater often found in reconstituted tobacco sheets due to the presence of air trapped within the slurry matrix during casting. "Tobacco dust" -- minute tobacco particles, i.e., in a range from about 2,5 mm to about 40 pm, created by tobacco breakage during the many manufacturing processes involving tobacco. The particles may be leaves, stems and the like from tobacco.

[0109] "Humectants" -- hygroscopic agents, such as glycerin and other glycols, that are often added to tobacco to assist in moisture retention and plasticity.

[0110] "Survivability" -- the ability of a reconstituted tobacco sheet to withstand the rigors of processing while creating a minimal amount of tobacco dust by-product.

Claims

Claims1 . A method for embossing with a set of embossing rollers- a reconstituted drug sheet (2500) of at least a drug embedded in a binder, having a determined sheet thickness, in view of obtaining- a pre-rod drug sheet (2507) with at least a folding enabling zone and at least a stiffening zone, each extending as a corresponding stripe on the prerod drug sheet in a feed direction through the set of embossing rollers,- the pre-rod drug sheet being intended to being folded into a rod, the rod being for use in a drug delivery product,- at least one of the folding enabling zone and the stiffening zone comprising embossed structures aligned in the feed direction, the embossed structures being configured depending on whether they are in the folding enabling zone or the stiffening zone, as folding enabling embossed structures and stiffening embossed structures to enable the folding of the pre-rod drug sheet or the stiffen the rod respectively, and in view of preserving an integrity of the pre-rod drug sheet, the method comprising providing (2501) the reconstituted drug sheet, providing (2502) an embossing device with the set of embossing rollers comprising at least a first and a second embossing roller separated by a nip, feeding (2503) the reconstituted drug sheet in the feed direction into the nip, providing (2504) patrix-matrix embossing features of positive and negative projections, on the first and the second embossing rollers, each of the patrix and matrix embossing features on the first embossing roller has a corresponding congruent counterpart on the secondembossing roller, producing the nip to have a substantially constant value, each of the patrix and matrix embossing features on the first embossing roller and on the second embossing roller has a structure profile in which any curvature radius has a minimum value of 40 pm, and any profile depth or profile height is smaller than twice the determined sheet thickness, thereby enabling the patrix and matrix embossing features on the first embossing roller and on the second embossing roller to consistently and gaplessly be in contact with both sides of the reconstituted drug sheet in the nip, providing (2505) for the at least one of the folding enabling zone and the stiffening zone respectively folding enabling embossing features and stiffening embossing features as patrix-matrix embossing features, and aligning them on the first and second embossing roller in a radial manner configured to emboss the corresponding stripe on the pre-rod drug sheet, and embossing (2506) the reconstituted drug sheet in the nip to obtain the pre-rod drug sheet (2507).

2. The method according to claim 1 , wherein the reconstituted drug sheet comprises reconstituted tobacco.

3. The method according to any one of claims 1 and 2, further comprising providing a bobbin of reconstituted drug sheet; and unwinding the reconstituted drug sheet towards the set of embossing rollers.

4. The method according to any one of claims 1 to 3, further comprisingmachining surfaces of patrix and matrix embossing features to provide them with a surface roughness Rawith a value equal or smaller than 1 pm.

5. The method according to any one of claims 1 to 4, further comprising spraying the reconstituted drug sheet with a humectant prior to feeding the reconstituted drug sheet in the feed direction into the nip, in order to improve a sheet cohesion and prevent an occurrence of sheet breakage and defective areas on the reconstituted drug sheet.

6. The method according to any one of claims 1 to 5, further comprising generating a gas stream and directing the gas stream towards the nip between the first and the second embossing rollers, the gas being any one from a list comprising hot air, water vapor, a gaseous matter, the gas locally heating the nip between the two embossing rollers, configured to facilitate a detachment of the pre-rod drug sheet from the embossing rollers, and preventing an occurrence of sheet breakage and defective areas.

7. The method according to any one of claims 1 to 6, further comprising providing an embossing roller cleaning tool in form of scrappers attached to a support of the embossing rollers, and configured to apply a scrapper edge congruent to the embossing features on any one of the embossing rollers, and remove potential debris originating from the reconstituted drug sheet from the embossing roller.

8. The method according to any one of claims 1 to 7, further comprising: providing stiffening patrix-matrix embossing features, whereby on one roller the patrix embossing features are configured to form protrudingsegments of ridges distinct from each other, and oriented under an angle in a range of 30° to 90° with respect to a radial orientation.

9. The method according to any one of claims 1 to 7, further comprising: providing stiffening patrix-matrix embossing features, whereby on one roller the patrix embossing features are configured to form protruding segments of ridges distinct from each other and extending from one longitudinal side of the stripe to an opposite side of the stripe, and oriented under an angle in a range of 30° to 90° with respect to a radial orientation.

10. The method according to any one of claims 1 to 7, further comprising: providing folding patrix-matrix embossing features, whereby on one roller the patrix embossing features are configured to form at least a protruding ridge on a surface of the one embossing roller, whereby the at least one protruding ridge is any one of continuous, and dis-continuous, the at least one protruding ridge being radially oriented around the one embossing roller.

11. A system for embossing a reconstituted drug sheet (302) of at least a drug (101) embedded in a binder (102), having a determined sheet thickness with a set of embossing rollers (304, 305) in view of obtaining- a pre-rod drug sheet (306) with at least a folding enabling zone (1201) and at least a stiffening zone (1202), each extending as a corresponding stripe on the pre-rod drug sheet (306) in a feed direction (1104) through the set of embossing rollers,- the pre-rod drug sheet (306) being intended to being folded into a rod (310), the rod (310) being for use in a drug delivery product,- at least one of the folding enabling zone (1201) and the stiffening zone (1202) comprising embossed structures (1301, 1401 , 1402, 1501 , 1502, 1601 , 1602) aligned in the feed direction (1104), the embossed structures being configured depending on whether they are in the folding enabling zone (1201) or the stiffening zone (1202), as folding enabling embossed structures and stiffening embossed structures to enable the folding of the pre-rod drug sheet or to stiffen the rod respectively, and in view of preserving an integrity of the pre-rod drug sheet (306), the system comprising an embossing device with the set of embossing rollers (304, 305) comprising at least a first (304) and a second (305) embossing roller separated by a nip (312, 1106), and configured to receive the reconstituted drug sheet (302) in the feed direction (1104) into the nip (312, 1106), patrix-matrix embossing features of positive (1107) and negative (1108) projections, on the first (304) and the second (305) embossing rollers, whereby each of the patrix (1107) and matrix embossing features on the first embossing roller (304) has a corresponding congruent counterpart (1108) on the second embossing roller (305), producing the nip (312, 1106) to have a substantially constant value, each of the patrix and matrix embossing features on the first embossing roller and on the second embossing roller has a structure profile in which any curvature radius (R) has a minimum value of 40 pm, and any profile depth or profile height is smaller than twice the determined sheet thickness, thereby enabling the patrix and matrix embossing features on the first embossing roller and on the second embossing roller to consistently and gaplessly be in contact with both sides of the reconstituted drug sheet in the nip,further wherein the at least one of the folding enabling zone and the stiffening zone comprises respectively folding enabling embossing features and stiffening embossing features as patrix-matrix embossing features, aligned on the first and second embossing roller in a radial manner configured to emboss the corresponding stripe on the pre-rod drug sheet.

12. The system according to claim 11 , further comprising a bobbin of reconstituted drug sheet configured to unwind the reconstituted drug sheet towards the set of embossing rollers.

13. The system according to any one of claims 11 to 12, wherein surfaces of the patrix-matrix embossing features are configured to have a surface roughness Rawith a value equal or smaller than 1 pm.

14. The system according to any one of claims 11 to 13, further comprising a humectant spraying system configured for spraying the reconstituted drug sheet with a humectant prior to feeding the reconstituted drug sheet in the feed direction into the nip, in order to improve a sheet cohesion and prevent an occurrence of sheet breakage and defective areas on the reconstituted drug sheet.

15. The system according to any one of claims 11 to 14, further comprising a blower unit configured to generate a gas stream and to direct the gas stream towards the nip between the first and the second embossing rollers, the gas being any one from a list comprising hot air, water vapor, a gaseous matter, the gas locally heating the nip between the two embossing rollers, configured to facilitate a detachment of the pre-rod drug sheetfrom the embossing rollers, and preventing an occurrence of sheet breakage and defective areas.

16. The system according to any one of claims 11 to 15, further comprising an embossing roller cleaning tool in form of scrappers attached to a support of the embossing rollers, and configured to apply a scrapper edge congruent to the embossing features on any one of the embossing rollers, and remove potential debris originating from the reconstituted drug sheet from the embossing roller.

17. The system according to any one of claims 11 to 16, wherein the stiffening patrix embossing features on one roller are configured to form protruding segments of ridges distinct from each other, and oriented under an angle in a range of 30° to 90° with respect to a radial orientation.

18. The system according to any one of claims 11 to 16, wherein: the stiffening patrix embossing features on one roller are configured to form protruding segments of ridges distinct from each other and extending from one longitudinal side of the stripe to an opposite side of the stripe, and oriented under an angle in a range of 30° to 90° with respect to a radial orientation.

19. The system according to any one of claims 11 to 16, wherein: the folding patrix embossing features on one roller are configured to form at least a protruding ridge on a surface of the one embossing roller, whereby the at least one protruding ridge is any one of continuous, and dis-continuous, the at least one protruding ridge being radially oriented around the one embossing roller.

20. The system according to any one of claims 11 to 19, wherein: the first embossing roller and the second embossing roller consist of a bulk metallic matter and exhibit a surface hardness larger than 50 HRC.

21. The system according to any one of claims 11 to 20, wherein: at least one of the first embossing roller and the second embossing roller is coated with a vacuum-deposited hard-coating, which exhibits a coating thickness smaller than 10 pm and a coating hardness greater than 500 MPa, and which belongs to a list containing diamond-like carbon, nitrides, carbides, oxides, and combinations thereof.

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